Classic Computer Magazine Archive CREATIVE COMPUTING VOL. 11, NO. 8 / AUGUST 1985 / PAGE 91

Password protect, less pricey Pivot, improved LCD for DG-1, RAM cards for Model 100 and NEC. (Notebook Computing) John J. Anderson.

When I first shared with you a password protect program I had written for the Model 100 (December 1984), I thought the practical advantages of such a program were enough to justify it. Since then, I have grown to appreciate the topic purely on the basis of its academic challenge. In the March 1985 column, I noed that Mark Cridland had punched a hole in my defenses, using the dedicated PRINT key, and it was back to the drawing board--not because I felt that many unauthorized users would actually find this sneaky chink in my program's armor, but because the search for the truly bulletproof security program is a noble one.

The other day I found the following message on Creative Computing Online:

"Just want to make you aware that a crack-proof machine code "log-on" program for the Tandy Model 100 is now available on the CompuServe Model 100 SIG (PSWDM.100 in Data Library 4). The program is self-loading from Basic, self-IPLing, and occupies a mere 237 bytes at the top of user memory when loaded. The program was born from a business need to protect my M100 text files from access (I work with a lot of confidential data). I have able to bypass all the Basic programs. I have found by quick stabs at the BREAK key before it is disabled, overflowing string storage with legnthy input, or other devious means, so I resorted to writing my own program using an assembler. I had to revise my first attempt after reading your column in Creative and discovering that the ROM routine I was using for character input could indeed be interrupted by the PRINT key (which reenables BREAK). The current version monitors the keyboard buffer directly without calling the break-check routine (which enables the screen dump interrupt). So far, I haven't found any way around it, short of killing the power to RAM.

"A listing of the 8085 assembly mnemonics with comments (PSWDM.ASM) is also available in DL4, and demonstrates how to exploit several useful ROM routines. I have been informed that experimenting with bypass strategies (e.g. pushing the reset switch twice while the menu is coming up if the program is IPLing) can result in mangling of RAM files and/or a cold start, so do warn your readers to back up their files before playing detective. I haven't discovered any other destructive behavior.

"Love your magazine, love your column, and of course I love my Model 100. Keep up the excellent work!--Keith Bergendorff 72306,322"

A day or so later I got the following update from Keith:

"Just a note to let you know I've upgraded my MC password program the to popular demand--new features are variable length ID code (1-8 characters), automatic power-down after 60 seconds, and more efficient 8085 coding. Still weighs in at less th an 250 bytes.--KB"

I couldn't find a way through Keith's password protect program--can you? The creator program for it appears here as Listing 1. Have a go at it, but bear Keith's warnings in mind.

Morrow Cuts Pivot by $1000

A $1000-per-unit price reduction on Morrow's Pivot portable computer is the company's first step in a no-risk-program to let users buy current Pivot models with 16-line displays, trading them in later for upgraded 25-line versions.

The program calls for the price of Pivot Model 1622 with 256K bytes of RAM and two floppy disk drives to be reduced from $2995 to $1995; the Model 1662, and 640K and two floppies, drops from $3795 to $2795. Users will be able to trade in one of these models plus $1000 for the 25-line version of the Pivot after July 15, 1985.

According to company chairman George Morrow, the program ensures that users can enter the portable arena immediately, without running the risk of short-term product obsolescence.

He adds that the new 25-line display upgrade will be only one key feature of the new Pivot, which will be a "significant redesign of the original . . . a design that provides 100% IBM PC compatibility." To ensure display legibility, the new Pivot screen combines the quality of an electro-luminescent display with the low cost and power consumption of a liquid crystal display. Its white characters on a black background are crisp and easy to read under any lighting conditions.

We reviewed the original Pivot in the April 1985 issue of Creative Computing. That machine sports a CMOS 80C86 16-bit microprocessor and industry-standard MS-DOS 2.11, in an 11-pound package, measuring 13" x 5.6" x 9.5" It offers as standard ROM-based utilities six executive productivity functions, including personal appointment scheduler, phone directory, and calculator.

Screen Update for DG/1

Data General is shipping an improved, tilt-version of the original LCD that was a part of the Data General/One portable. That machine was reviewed in the February 1985 issue and had come under criticism for a relatively poor quality 25-line display.

The new LCD, also available as an upgrade for current DG/1 models, optimizies screen polarization, which substantially improves contrast quality. A continuous tilt adjustment lets users vary the viewing angle to obtain maximum screen clarity while minimizing glare. This increases readability in a wide range of lighting conditions.

The suggested list price for upgrades is $350. Owners may either return their current units to DG for upgrade or bring the units to authorized dealers. The procedure can normally be completed in 30 minutes.

New production units already feature the improved display, and have not affected the $2895 base price of the DG/1.

96K Model 100

PG Design Electronics has introduced 32K and 64K RAM modules for the Radio Shack Model 100. The modules fit neatly in the expansion compartment of the Model 100 and add RAM in banks of 32K to a maximum of 96K.

Each bank can be accessed from any of the other banks, and an optional data transfer program is available. The layout of the RAM module leaves the Model 100 ROM slot clear for use. The Video Disk Interface is provided for with a rugged, standard 40-pin connector.

The 32K module lists for $250, while the 64K module lists for $375. The 32K version may be upgraded at a later time for $150.

128K NEC 8201

Purple Computing has announced an expandable memory cartridge called the Sidecar for the NEC 8201 portable. Unlike NEC's own 32K plug-in memory cartridge, the Sidecar cartridge is expandable to 128K organized as four banks of 32K.

The Sidecar plugs into the same slot as the NEC 32K cartridge and contains two standard AA batteries to maintain CMOS RAM when the computer is powered down. The batteries will last a year or more and can be replaced without loss of data.

The single unit list price for the basic 32K Sidecar is $349. User installable 32K banks are $145 for bank two, $175 for banks three and four. The Sidecar carries a one-year warranty.